Hybrid drives for vehicles are known. In the hybrid drives claimed here, an internal combustion engine is combined with at least one electric motor so that multiple drive sources are provided for the vehicle. According to the requests specified by a vehicle driver, the drive sources can optionally supply their drive moments to a drive train of the vehicle. Depending on the actual driving situation, this results in various drive configuration possibilities for the drive, in a manner known as such, which in particular are used for improving driving comfort and reducing energy use as well as pollutant emissions.
In hybrid drives for vehicles, serial configurations, parallel configurations, and mixed configurations of an internal combustion engine and electric motors are known. Depending on the configuration, the electric motors may be directly or indirectly coupled to the drive train of the internal combustion engine. For the mechanical linkage of the internal combustion engine and/or the electric motors, it is known to provide these with a mechanically linkable configuration via gearing, for example planetary gears or the like, and clutches.
It is known that the internal combustion engine functions as the main drive source for the vehicle, while the electric motors, depending on the actual driving situation, may be engaged or disengaged. In drive designs it is known that for a negative torque request by a vehicle driver the internal combustion engine delivers a drag torque which is determined by the internal losses in the internal combustion engine as a function of an instantaneous engine rotational speed. If the gears are changed during the negative torque requests by the vehicle driver, for example in the operation of a manual transmission or actuation of a hydrodynamic converter (automatic transmission), abrupt variations in the output torque of the drive result on account of the abrupt change in the rotational speed acting on the drive train (corresponding to the gear position selected). This is caused by the fact that the drag torque of the internal combustion engine is a function of the rotational speed.